title: Requirement for active glycogen synthase kinase-3β in TGF-β1 upregulation of connective tissue growth factor (CCN2/CTGF) levels in human gingival fibroblasts.
abstract: Connective tissue growth factor (CCN2/CTGF) mediates transforming growth factor-β (TGF-β)-induced fibrosis. Drug-induced gingival overgrowth is tissue specific. Here the role of the phosphoinositol 3-kinase (PI3K) pathway in mediating TGF-β1-stimulated CCN2/CTGF expression in primary human adult gingival fibroblasts and human adult lung fibroblasts was compared. Data indicate that PI3K inhibitors attenuate upregulation of TGF-β1-induced CCN2/CTGF expression in human gingival fibroblasts independent of reducing JNK MAP kinase activation. Pharmacologic inhibitors and small interfering (si)RNA-mediated knockdown studies indicate that calcium-dependent isoforms and an atypical isoform of protein kinase C (PKC-δ) do not mediate TGF-β1-stimulated CCN2/CTGF expression in gingival fibroblasts. As glycogen synthase kinase-3β (GSK-3β) can undergo phosphorylation by the PI3K/pathway, the effects of GSK-3β inhibitor kenpaullone and siRNA knockdown were investigated. Data in gingival fibroblasts indicate that kenpaullone attenuates TGF-β1-mediated CCN2/CTGF expression. Activation of the Wnt canonical pathways with Wnt3a, which inhibits GSK-3β, similarly inhibits TGF-β1-stimulated CCN2/CTGF expression. In contrast, inhibition of GSK-3β by Wnt3a does not inhibit, but modestly stimulates, CCN2/CTGF levels in primary human adult lung fibroblasts and is β-catenin dependent, consistent with previous studies performed in other cell models. These data identify a novel pathway in gingival fibroblasts in which inhibition of GSK-3β attenuates CCN2/CTGF expression. In adult lung fibroblasts inhibition of GSK-3β modestly stimulates TGF-β1-regulated CCN2/CTGF expression. These studies have potential clinical relevance to the tissue specificity of drug-induced gingival overgrowth.
authors.affiliation: Boston University Henry M. Goldman School of Dental Medicine, Department of Periodontology and Oral Biology, Boston, Massachusetts.
authors.forename: Maha
authors.initials: M
authors.lastname: Bahammam
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Black
authors.forename: Siddika Selva
authors.initials: SS
authors.lastname: Sume
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Assaggaf
authors.forename: Michael
authors.initials: M
authors.lastname: Faibish
authors.forename: Philip C
authors.initials: PC
authors.lastname: Trackman
mesh_terms: D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism*; D005347:Fibroblasts / Q000201:enzymology / Q000378:metabolism*; D005881:Gingiva / Q000201:enzymology / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D020935:MAP Kinase Signaling System; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation; D060509:Wnt3A Protein / Q000235:genetics / Q000378:metabolism; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism
chemical_list: D055513:Connective Tissue Growth Factor; D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C; D053773:Transforming Growth Factor beta1; D060509:Wnt3A Protein; D051176:beta Catenin; C526317:CCN2 protein, human; C555510:WNT3A protein, human; C000605506:GSK3B protein, human
keywords: CCN2; GSK-3β; connective tissue growth factor; gingival growth; transforming growth factor